Pain in infants is under diagnosed, yet preterm infants in intensive care (NICU) experience repeated painful procedures. Tissue damage from heel lances, intravenous punctures, and other standard caregiving procedures results in permanent structural changes in the brain and spinal cord during a period of rapid brain growth. The stress of painful and other noxious procedures places infants at increased risk of infections due to their already compromised immune system and may have long lasting effects on their growth and development. Methods of pain management should be matched to the type and duration of pain experience. Numerous non-pharmacological approaches designed to enhance an infants' own self regulation behavior can be provided for transient painful procedures. No study has examined the stability of individual patterns of responses to painful procedures, and only two studies have compared infant responses to painful versus standard caregiving procedures. The specific aims of this intensive within-subject longitudinal study are to examine the stability of infant responses to painful and standard caregiving procedures normally experienced by preterm infants in an NICU, and to determine optimal recovery time to baseline before additional caregiving is provided. Four groups totaling 80 preterm infants between 23 and 34 weeks gestation age will be recruited shortly after admission to the NICU. Real time videotaping and computer acquisition of physiological data will occur for at least one five hour period everyday for the first week and then once a week until the infant is discharged. The total number of painful and standard procedures the infant receives will be documented from the chart and verified with 24 hour time lapse video on a random basis. Analysis of variance, regression analysis, spectral analysis and qualitative tape analysis will be used to determine individual and group patterns of responses to painful and standard procedures. The results will add significant information regarding the stability, type and duration of infant pain responses and facilitate decisions regarding the most appropriate type of pain management.